title: Role of attenuation correction to discriminate defects caused by left bundle branch block versus coronary stenosis in single photon emission computed tomography myocardial perfusion imaging.
abstract: OBJECTIVE
  To define the impact of attenuation correction (AC) on interpretation of perfusion abnormalities induced by left bundle branch block (LBBB) in myocardial perfusion imaging (MPI) and single photon emission computed tomography (SPECT).
  
  
  METHODS
  Thirty-six patients with spontaneous and 12 with pacemaker (PM)-induced LBBB (mean age 68.6 +/- 9.7) underwent gated 1-day adenosine stress/rest Tc-99m tetrofosmin SPECT on a hybrid SPECT-CT dual-head detector camera with Hawkeye facility (Infinia, GE Healthcare, Milwaukee, WI). Images were analyzed using iterative reconstruction (IR) and AC by computerized tomography (IR-AC) and compared with filtered back protection (FBP) as a standard of reference. Defect extent and severity for the anterior, septal, apical, inferior, and lateral regions were assessed by computerized analysis. The combination of septal with anterior and/or apical perfusion defects was attributed to the typical LBBB-induced pattern.
  
  
  RESULTS
  LBBB caused a typical perfusion pattern in 24 patients with spontaneous and in 10 with PM-induced LBBB, whereas MPI was normal in 14 patients. FBP revealed a partial reversibility of anterior (spontaneous LBBB) and apical-septal (spontaneous and PM-induced LBBB) defect severity. By IR-AC, LBBB caused comparable anteroseptal reversible perfusion defects (P < 0.05) but fixed apical defects. Apical-septal defect severity was higher and defect extent was larger in IR-AC compared with FBP (both P < 0.05). Defect extent was unchanged between rest and stress for both reconstructions.
  
  
  CONCLUSIONS
  Spontaneous and PM-induced LBBB often induces typical perfusion defects in MPI at stress, partly reversible at rest. With IR-AC this typical pattern is more pronounced and less reversible, strengthening the confidence to discriminate such findings from ischemia.
authors.affiliation: Cardiovascular Center, University Hospital Zurich, Zurich, Switzerland.
authors.forename: Tobias
authors.initials: T
authors.lastname: Hoefflinghaus
authors.forename: Lars
authors.initials: L
authors.lastname: Husmann
authors.forename: Ines
authors.initials: I
authors.lastname: Valenta
authors.forename: Clemens
authors.initials: C
authors.lastname: Moonen
authors.forename: Oliver
authors.initials: O
authors.lastname: Gaemperli
authors.forename: Tiziano
authors.initials: T
authors.lastname: Schepis
authors.forename: Mehdi
authors.initials: M
authors.lastname: Namdar
authors.forename: Pascal
authors.initials: P
authors.lastname: Koepfli
authors.forename: Patrick T
authors.initials: PT
authors.lastname: Siegrist
authors.forename: Philipp A
authors.initials: PA
authors.lastname: Kaufmann
mesh_terms: D000368:Aged; D002037:Bundle-Branch Block / Q000000981:diagnostic imaging / Q000503:physiopathology*; D017023:Coronary Angiography; D023921:Coronary Stenosis / Q000000981:diagnostic imaging / Q000503:physiopathology*; D003937:Diagnosis, Differential; D004562:Electrocardiography; D005080:Exercise Test; D005260:Female; D015637:Gated Blood-Pool Imaging; D006321:Heart / Q000000981:diagnostic imaging / Q000503:physiopathology; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009943:Organophosphorus Compounds; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*
chemical_list: D009943:Organophosphorus Compounds; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; C078700:technetium tc-99m tetrofosmin